Abstract Background Early stage Non-Small Cell Lung Cancer (NSCLC) is potentially curable with surgery. ESMO guidelines recommend cisplatin-based adjuvant chemotherapy (CT) for completely resected stage II–III NSCLC. There is limited evidence for the use of adjuvant CT and/or radiotherapy (RT) in incompletely resected (R1) early stage NSCLC. Materials and methods A European survey of thoracic oncologists was conducted to evaluate use of adjuvant CT and RT for R1-resected NSCLC and to identify factors influencing treatment decisions. Demographics and information on clinical stage, regimens, cycles planned, radiotherapy sites, multidisciplinary management and discussion about inconclusive evidence with the patient were collected. Univariate and multivariate analyses were performed. Results 768 surveys were collected from 41 European countries. 82.9% of participants were medical oncologists; 49.3% ESMO members; 37.1% based in University Hospitals; 32.6% practicing oncology for over 15 years and 81.4% active in research. 91.4% of participants prescribed adjuvant CT and mostly cisplatin/vinorelbine (81.2%) or cisplatin/gemcitabine (42.9%). 85% discussed limited clinical evidence with the patient. In the univariate analysis, a statistically significant association with CT prescription was found for medical oncology specialty (p<0.001), ESMO membership (p<0.001), activity in clinical research (p=0.002) and increased frequency of ESMO guidelines consultation (p for trend <0.001). 48.3% of participants prescribed adjuvant RT and its prescription were associated with radiation oncology specialty (p<0.001), not being an ESMO member (p<0.001), years practicing specialty (p for trend=0.001), workload of lung cancer patients (p for trend=0.027) and decreased frequency in consulting ESMO guidelines (p<0.001). In the multivariate analysis, medical oncology and radiation oncology were the best discriminator for prescription of adjuvant CT and RT, respectively. Conclusion This survey demonstrates that adjuvant CT and RT are commonly used in clinical practice for R1-resected NSCLC despite limited evidence. Prospective trials are necessary to clarify optimal management in this setting.